In a conventional information storage and retrieval system, users present to the system requests for search. If the system determines via an index that a document matches the search criteria, access to the document is provided to the user who requested the search. Generally, documents that contain confidential information are not made available for access in this manner, unless all users and potentially the entire network are under the administration of a single authority that can bind the users to secrecy by contract. For example, all employees using an intranet hosted by an employer may search the employer's confidential information protected from disclosure by employment agreements.
Searches that disclose confidential information via public networks have been suggested with the limitation that the search criteria and the indexes are consistently encrypted.
Storage and retrieval systems that span a public network have also been suggested where access is limited to subscribers. Subscribers are trusted with disclosures of confidential information because they have agreed to the terms of a subscription agreement related to the services provided by an authority managing the system.
These technologies, however, do not economically offer sufficient flexibility and protection to facilitate greater cooperation between agencies and agents.